High tension discharge tube



March 8, 1938. A. BOUWERS Z Q I HIGH TENSION DISCHARGE TUBE Filed Nov. 16, 1933 2 Sheets-Sheet 1 5' iffam y March 8, 1938. BOUWERS HIGH TENSION DISCHARGE TUBE 2 Sheets-Sheet 2 Patented Mar. 8, 1938 UNITED STATES PATENT OFFICE Albert Bouwers, Eindhoven,

Netherlands, as-

signor, by mesne assignments, to N. V. Philips Gloeilampenfabrieken, Eindhoven, Netherlands,

a Dutch company Application November 16, 1933, Serial No. 698,379 In Germany December 2, 1932 13 Claims.

My invention relates to high-tension discharge tubes and more particularly to X-ray tubes.

While I shall describe my invention as applied to X-ray tubes, it is not limited thereto but is adapted for use in high-tension discharge tubes in general.

One object of my invention is to reduce the size of such high-tension tubes, and to eliminate the dangers caused by the high operating-voltage.

Another object of my invention is to provide high-tension discharge tubes of such a shape that their use is greatly facilitated.

A further object of my invention is to connect a high-tension discharge tube to supply 1 leads in a simple manner whereby a minimum amount of material is used without decreasing the electrical protection of the tube.

As stated above, my invention is particularly adapted for use with X-ray tubes, as with such tubes a small size and a shock-proof construction is of great importance.

In accordance with the invention, I form the exposed portions of the Wall of the tubes of metal or an insulating material provided with a metal coating which may be grounded, and support the electrodes from reentrant parts of insulating material secured to the ends of the exposed wall portions. The reentrant parts take up the electrostatic load and also serve to support supply conductors for the electrodes which conductors are insulated from ground for the full tension of the tube.

As the reentrant parts take up substantially the entire potential difference between the electrodes, they can be brought very close together with the result that the supply conductor will also be brought close together. Due to this the tube may be given a U or V shape which, in the case of X-ray tubes, greatly facilitates. their use.

To further increase the insulating capacity I fill the hollow spaces between the reentrant parts and the supply conductors with a liquid or solid insulating material.

The invention will be more clearly understood by reference to the accompanying drawings representing, by way of example, some forms of construction thereof.

Figure l is a side view partly in section and with parts broken away, of an X-ray tube in ac cordance with the invention. 1

Fig. 2 is a side view partly in section, showing an X-ray tube which is rotatably mounted and having a V-shape.

Fig. 3 is a side-view, partly in section, of an X-ray tube having a U-shape.

The X-ray tube shown in Fig. 1 has an em velope consisting of an equipotential portion l0 and two vitreous reentrant portions 4 and 5 sealed to the ends of portion l0 and carrying an anode structure 2 and a cathode structure 3 respectively. The portion H! has the form of a metal case, which insures that this portion of the tube will have the same potential throughout.

Instead of making the portion NJ entirely of metal it may consist of a wall of insulating material provided with a conductive coating. Thus, in referring to an equipotential portion it is to be understood that this is meant to include both a portion made entirely of metal, and a portion consisting of insulating material provided with a conductive coating. It is well known in the art of making high-voltage discharge tubes to provide a conductive-surface over a portion of the wall, especially the portion surrounding the discharge path.

A particular feature of my invention is that the conductive surface extends over the entire outer or exposed portion of the tube whereas the hightension is taken up entirely by the reentrant portions 4 and 5 which are made of insulating material such as glass. Furthermore, all parts of the tube having a potential difference with the equipotential portion are surrounded by the equi potential portion whereby it is unnecessary to provide a protective housing to prevent one from coming too close to the high-tension parts. Due to this a shock-proofed tube is obtained without employing a protective housing.

The reentrant portions 4 and 5 are given a sufficiently large inside diameter to receive supply conductors 6 and 1 respectively together with insulating members 8 and 9. surrounding conductors 6 and 1 respectively. The insulating members 8 and 9 serve to prevent sparking-over under the influence of the electric field set up between the supply conductors 6 and l and the equipotential portion ill. The portion Ed has secured to it two terminal caps ii and i2 provided with side arms [3 and Hi respectively which extend parallel with each other and normal to the longitudinal axis of the X-ray tube and serve for securing the terminal parts 15 and it of the cables. Although in Fig. l, the insulation of conductors 6 and l is effected by funnel shaped members 8 and 9 of solid insulation material, it may also be formed by a liquid insulating material filling up the whole space bounded by the reentrant portions 4 and 5 and the terminal caps H and i2 respectively. Since part of the outer wall of the envelope which surrounds the discharge space consists entirely of metal and is grounded, a protecting envelope is superfluous, and in addition the size of the complete X-ray tube is extremely small. The tube can be easily handled and the window I! serving for the passage of the rays is readily accessible.

The X-ray tube represented in Fig. 2 comprises two metal tubes 2| and 22 connected in' the form of a V. The potential difference between the electrodes 41 and 48 and the tubes 2! and 22 is taken up by the insulating re-entrant parts 23 and 24. The potential of the metal part of the tube wall formed by tubes 2! and 22 may lie approximately half way between the potentials of the electrodes. The supply conductors are surrounded by solid insulators 25 and 26 which are constructed as inlet insulators and traverse a turn disc 21' to which the tubes 25 and 22 are secured by means of flanged joints.

The turn disc 21 bears on guide rollers 46 movably supported in a race of the partition wall between the chamber in which the irradiation is effected and that wherein the generation of the high tension occurs in such a manner that the X-ray tube is rotatable about an axis which bisects the angle between the axes of the reentrant parts. If desired, the rotatory disc may also be made to be movable in an upward direction. The anticathode mirror is at an angle of 45 with this axis and inclined with respect to a direction normal to this axis and to the main direction of the cathode rays so that X-rays emerging in an axial direction and in a direction normal thereto can be used. The window serving for irradiation in an axial direction is denoted by 28 in the drawings. The insulators 25 and 26 have secured to them travelling rollers 29 and St for flexible conductors owing to which the rotation of the X-ray tube is not hindered within wide limits by the supply conductors.

The U-shaped X-ray tube represented in Fig. 3 also has a metal outer Wall and legs 3| and 32 which enclose the glass reentrant parts 33 and 3 surrounding the supply conductors 35 and 38 of the cables. These cables extend to the electrodes, namely the cathode 31 and the anode 38. Ihe discharge path is normal to the axial direction of the re-entrant parts 33 and 34. In contradistinction to both other forms of construc tion the anode of the tube is provided with a slightly inclined frontal surface whereon a linear focus is formed. The focal spot appears materially shortened when projected through the window 39. The supply cables are provided with grounded coatings which do not extend into the rcentrant part. Furthermore metal rings ill and ll are provided which form an uninterrupted continuation of the internal surface of said coatings and on which bear rings t2 consisting of plastic insulating material, for instance of rubber. The space between said insulating rings and the bent edge of the re-entrant parts is fill d up with oil or an insulating material 43. The metal rings and G! are firmly pressed by cap nuts it and 45 which are screwed on the upper ends of the legs 3! and 32 so that the insulating rings are duly arranged and the insulating material or the oil 43 penetrates into the spaces between the cables and the re-entrant parts. In this mann r the cables are fixedly connected to the metal vessel of the tube and at the same time sufiicient protection against breakdown is obtained.

What I claim is:

1. An electric discharge tube for high tension, having an enclosing envelope and electrodes mounted therein, said envelope comprising a U- shaped tube forming substantially all of the exposedexterior surface of the discharge tube and having conductive and electrically interconnected inner and outer surfaces, and also comprising reentrant portions extending inside the legs of said U-shaped tube, said re-entrant portions consisting of insulating material and carrying the electrodes, high tension insulators extending into the said re-entrant portions, and high tension supply conductors passing through the said insulators to the electrodes of the tube.

2. An X-ray tube comprising an anode structure, a cathode structure and an enclosing envelope, said envelope comprising a U-shaped tube forming substantially all of the exposed exterior surface of the X-ray tube and having inner and outer conductive surfaces which are electrically interconnected and also comprising re-entrant portions, said re-entrant portions carrying the electrodes and insulating same from said U- shaped. tube, said electrodes being spaced from each other to form a discharge gap in the base portion of said U-shaped tube, two high tension cables each comprising a conductive core, an insulating layer and a metal sheath, said cable sheath being connected to the conductive surface of said U-shaped tube, and said insulating layer and cores extending into said reentrant portions, each electrode of the tube being connected to one of said cores.

3. A shock-proof high tension discharge tube having an enclosing envelope, electrodes mounted therein, and supply conductors for said electrodes and connected thereto, said envelope comprising a metal tubular member forming substantially all of the exposed exterior surface of the tube, a re entrant portion of vitreous material sealed to each end of the tubular member, each of said reentrant portions carrying one of said electrodes and surrounding the supply conductor of its electrode, the combined insulating capacity of said re-entrant portions being adapted to withstand the operating voltage existing between said electrodes, said supply conductors being covered by a high tension insulation which extends into the said re-entrant portions.

4. In combination an X-ray device having two electrode members and high tension supply cables therefor, said device comprising a tubular metal vessel forming substantially all of the exposed exterior surface of the tube and having a window for the exit of the X-rays and two sidetubes, said side-tubes extending parallel to each other and in a direction forming an angle with the direction of the X-ray beam, and being spaced from each other a distance smaller than their length, a glass tube mounted co-axially in each of said side-tubes, one end of each glass tube being flared and sealed edgewise to the surrounding side tube, and the opposite end of said glass tubes being sealed to one of said electrode members, said cables comprising a high tension insulation extending into said glass tubes, and a metal sheath surrounding said insulation, the metal sheath of the cable extending only to the edge of the side-tube facing the electrode member, and means for electrically and mechanically connecting the sheath with the side tube.

5. A shock-proof high tension discharge tube having an enclosing envelope and electrodes mounted therein, said envelope having an equipotential portion, and a re-entrant portion surrounded throughout the greater part of its length by said equipotential portion and carrying an electrode said equipotential portion forming substantially all of the exposed exterior surface of the tube, a supply conductor for said electrode surrounded by said re-entrant portion, said supply conductor having a coating of insulating material partly filling up said re-entrant portion, the outer surface of said coating being spaced from the walls of said re-entrant portion, and an insulation material of higher insulating capacity than air filling up the space between said coating and wall.

6. In combination an X-ray tube comprising a metal tube member forming substantially all of the exposed exterior surface of the X-ray tube, and two tubular glass members having flared rims at one end, said flared rims being edgewise sealed to the two ends of said metal tube, said glass members forming re-entrant portions within said metal tube, electrode members mounted one at each of the other ends of said glass members, said electrode members being spaced apart to form a discharge gap, insulators mounted within said glass members, and supply conductors passing through said insulators and connected to said electrode members, and metal cap members secured to the two ends of said metal tube, said cap members having apertures and high tension cables passing through said apertures and adapted to be secured to said insulators.

7. A shock-proof high-tension electric discharge tube comprising an enclosing envelope having a hollow equipotential portion forming substantially all of the exposed exterior surface of the tube, and insulating re-entrant portions extending into said equipotential portion, said equipotential portion surrounding the major part of said re-entrant portions, electrodes within said envelope and carried by said re-entrant portions, current-supply conductors for said electrodes extending through said reentrant portions, and insulation material surrounding said conductors and capable of withstanding the voltage difference existing between the respective conductor and said equipotential portion.

8. A shock-proof X-ray tube comprising an envelope having a hollow equipotential portion forming substantially all of the exposed exterior surface of the tube and extending substantially to the ends thereof, and two re-entrant portions of insulation material extending into said equipotential portion and surrounded thereby over substantially their entire length, an anode carried by one re-entrant portion, and a cathode carried by the other re-entrant portion.

9. A shock-proof high-tension electric discharge tube comprising an envelope having an equipotential wall portion forming substantially all of the exposed exterior surface of the tube, and hollow re-entrant portions of insulation material electrostatically loaded during operation, said re-entrant portions extending into said equipotential portion and being substantially surrounded thereby, electrodes within said envelope and carried by said re-entrant portions, and current conductors connected to said electrodes and extending into the space surrounded by said reentrant portions.

10. A shock-proof high-tension electric discharge tube comprising electrodes, an evacuated envelope having a hollow metal wall portion extending substantially to the ends of the tube, and hollow glass re-entrant portions extending from each end of the tube into said metal portion and surrounded thereby throughout substantially their entire length, each of said glass portions carrying one of said electrodes, and current-supply conductors connected to said electrodes and extending into the space surrounded by said glass portions.

11. A shock-proof high-tension electric discharge tube comprising an evacuated envelope having an equipotential wall portion forming substantially all of the exposed exterior surface of the tube, and hollow portions of insulation material extending into said equipotential portion and being surrounded thereby throughout substantially their entire length, electrodes within said envelope and carried by said insulating portions, current conductors connected to said electrodes and extending into the space surrounded by said insulating portions, and additional insulation material covering the inner surfaces of said insulating portions and having a greater insulating capacity than air.

12. A shock-proof X-ray tube comprising electrodes, an evacuated envelope comprising a tubular metal body forming substantially all of the exposed exterior surface of the tube, and reentrant glass tubular bodies sealed to the ends of said metal body and capable of withstanding high voltages between their ends, said glass bodies carrying said electrodes and being surrounded by said metal body throughout substantially their entire length, current conductors connected to said electrodes and extending into said tubular bodies to form a space therewith, insulating material of greater insulating capacity than air filling said space, high-tension supply cables electrically connected to said conductors, and means mechanically connecting said cables to said metal tubular body.

13. A shock-proof X-ray tube comprising electrodes, an evacuated envelope having a metal tubular body forming substantially all of the exposed exterior surface of the tube, and re-entrant glass tubular members sealed to the ends of said metal tubular body, said glass members being surrounded substantially throughout their entire length by said body, said re-entrant tubular members carrying said electrodes, hightension current conductors extending through said glass members and forming spaces therewith, insulating material filling said spaces, highvoltage supply cables electrically connected to said conductors, and metal caps secured on the ends of said metal tubular body and mechanically connecting said cables to said metal tubular member.

ALBERT BOU'WERSL 

